// The NSpring Framework for .NET
// Copyright (c) 2003, Jeffrey Varszegi
// All rights reserved.
// 
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// are permitted provided that the following conditions are met:
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// list of conditions and the following disclaimer.
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// materials provided with the distribution.
// 
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namespace NSpring.Logging.Filters {

using System;
using System.Text;
using System.Text.RegularExpressions;

/// <summary>
/// Provides a filter that accepts and rejects Event objects by matching on each Event's 
/// Message property using a System.Text.RegularExpressions.Regex instance.
/// </summary>
public sealed class RegularExpressionFilter : Filter {
    private Regex regex;
    private string regularExpression;
    
    private RegularExpressionFilter() {}
    
    /// <summary>
    /// Constructs a new instance that will use the specified string as its regular expression
    /// </summary>
    /// <param name="expression">The regular expression to use</param>
    public RegularExpressionFilter(string expression) {
        if (expression == null) {
            throw new ArgumentNullException();
        }
        regularExpression = expression;
        regex = new Regex(expression, RegexOptions.Compiled);
    }
    
    /// <summary>
    /// Constructs a new instance that will use the specified string as its regular expression
    /// </summary>
    /// <param name="expression">The regular expression to use</param>
    /// <param name="options">Options for the Regex instance created</param>
    public RegularExpressionFilter(string expression, RegexOptions options) {
        if (expression == null) {
            throw new ArgumentNullException();
        }
        regularExpression = expression;
        regex = new Regex(expression, options);
    }
    
    /// <summary>
    /// Gets and sets the text of the underlying regular expression
    /// </summary>
    public string RegularExpression {
        get {
            return regularExpression;
        }
        set {
            if (value == null) {
                throw new ArgumentNullException();
            }
            lock (this) {
                regex = new Regex(value);
                regularExpression = value;
            }
        }
    }
    
    protected override bool Matches(Event _event) {
        if (_event.Message == null) {
            return false;
        }
        else {
            return regex.IsMatch(_event.Message);
        }
    }
}

}
